Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Financial information for the Company's operating segments
Net interest income	$ 52,169	$ 34,404	$ 102,140	$ 67,785
Provision for loan losses	1,450	3,000	2,900	6,050
Noninterest income	19,471	17,317	38,087	34,695
Noninterest expense	49,396	37,734	97,041	75,334
Income before income taxes	20,794	10,987	40,286	21,096
Income taxes	5,941	2,968	11,836	5,506
Net income	14,853	8,019	28,450	15,590
Total assets	5,826,020	4,249,281	5,826,020	4,249,281	5,746,270
Goodwill	276,146	184,779	276,146	184,779	276,100
Community Banks
Financial information for the Company's operating segments
Net interest income	52,744	34,251	103,380	67,928
Provision for loan losses	1,501	2,990	2,890	5,907
Noninterest income	15,129	14,658	29,212	29,201
Noninterest expense	45,530	34,921	89,655	70,023
Income before income taxes	20,842	10,998	40,047	21,199
Income taxes	6,168	3,079	12,146	5,802
Net income	14,674	7,919	27,901	15,397
Total assets	5,744,942	4,183,079	5,744,942	4,183,079
Goodwill	273,379	181,996	273,379	181,996
Insurance
Financial information for the Company's operating segments
Net interest income	49	24	112	47
Provision for loan losses	0	0	0	0
Noninterest income	2,138	973	4,531	2,006
Noninterest expense	1,684	813	3,158	1,626
Income before income taxes	503	184	1,485	427
Income taxes	202	71	582	165
Net income	301	113	903	262
Total assets	17,864	10,460	17,864	10,460
Goodwill	2,767	2,783	2,767	2,783
Wealth Management
Financial information for the Company's operating segments
Net interest income	320	324	631	619
Provision for loan losses	(51)	10	10	143
Noninterest income	2,181	1,681	4,297	3,462
Noninterest expense	1,999	1,736	3,867	3,317
Income before income taxes	553	259	1,051	621
Income taxes	0	0	0	0
Net income	553	259	1,051	621
Total assets	46,259	42,886	46,259	42,886
Goodwill	0	0	0	0
Other
Financial information for the Company's operating segments
Net interest income	(944)	(195)	(1,983)	(809)
Provision for loan losses	0	0	0	0
Noninterest income	23	5	47	26
Noninterest expense	183	264	361	368
Income before income taxes	(1,104)	(454)	(2,297)	(1,151)
Income taxes	(429)	(182)	(892)	(461)
Net income	(675)	(272)	(1,405)	(690)
Total assets	16,955	12,856	16,955	12,856
Goodwill	$ 0	$ 0	$ 0	$ 0